Chicken bit by ferret(most likely)

Hey all, so I have a bunch of chickens as pets with benefits which live in a garden. they've been living there for years.

On Monday I went to feed them in the morning and found 10+ passed. I assume a ferret or something similar got to them..broke my heart. as I was picking them up, found my meat chicken huddled in a corner. brought her to the vet where she got stitches. she doesn't eat on her own and her head is droopy. any opinions?